Optimization Design And Comparative Study Of Magnetic Gear Motor With High Torque Density

New energy vehicle development is an important strategic initiative to effectively solve energy crisis,environmental pollution,and other problems,and achieve national ecological civilization construction.To satisfy the increasingly strict operation requirements of the new generation of electric vehicles,the research of motor driving system with high torque density and high integration density,has become a focus to promote the rapid development of the industry.Recently,based on the magnetic field modulation principle,magnetic gear motor(MGM)with potential advantages such as high torque density and high efficiency,has attracted the attention and interest of researchers in the field of drive motors.It is worthy that,the characteristics of PM magnetomotive force(PM-MMF)and armature magnetomotive force(Arm-MMF)are the key to determine the air gap magnetic field modulation effect.How to fully consider PM-MMF and Arm-MMF into motor design is an effective method to deeply explore the potential performance advantages and obtain high performance design of MGMs,which is also a hot and popular research direction.Therefore,a V-shaped MGM(V-MGM)with high torque density is proposed in this paper,and topology exploration,structure design and optimization are carried out.Based on the principle of magnetic field modulation,an in-depth analysis and comparative study of the proposed V-MGM and I-shaped MGM(I-MGM)is presented under the conditions of the same fundamental component of PM-MMF(FCPM-MMF),same fundamental component of Arm-MMF(FCArm-MMF),same FCPM-MMF and FCArm-MMF.The main contents of this paper are given as follows:Firstly,a new high torque density V-MGM is proposed.The V-MGM combines the interior PM motor with magnetic gear,which adopts the rotor structure with internal V-shaped PMs and external virtual slots and selects the appropriate pole-pair number.Secondly,based on the magnetic field modulation,the theoretical analysis model of MGM is established to reveal the working principle by using the air gap magnetic density as the bridge.In addition,the reasonableness of theoretical analysis is verified by finite element analysis,which establishes the foundation for optimization design.Thirdly,to improve the torque density of MGM and fully consider the characteristics of the magnetic field modulated motor,the optimization designs of two MGM motors have been studied from different PM-MMF and Arm-MMF.Based on the theoretical analysis of the magnetic field modulation theory,the key parameters to improve the utilization of the FCPM-MMF and the FCArm-MMF are designed.And thus,the optimal parameters of two MGMs under different conditions are obtained.Furthermore,the electromagnetic performance of V-MGM and I-MGM are systematically compared.Under the same FCPM-MMF,the influence of different FCArm-MMF on the MGM torque output performance is investigated.Under the same FCArm-MMF,the influence of different FCPM-MMF on PM utilization and eddy current loss are investigated.Under the same FCPM-MMF and FCArm-MMF,the electromagnetic performance of V-MGM and I-MGM are comprehensively analyzed and compared,including magnetic field distribution,air-gap magnetic density generated by MMF,back-electromotive force characteristics,torque characteristics,loss and efficiency,and power factor.The results show that V-MGM has higher torque density and better comprehensive electromagnetic performance.Finally,the corresponding prototype is manufactured according to the design parameters of the V-MGM,and the experimental test platform is built based on the operation characteristics of the MGM.And then the no-load back-electromotive force and steady torque current characteristics of V-MGM are tested.The experimental tests and the finite element analysis results under the same conditions verify the reasonability of the design and research.The above research results establish the foundation for potential applications of high torque density MGMs.